Method and arrangement for checking the alignment of a paper sheet in paper sheet feed apparatus

ABSTRACT

A method and an arrangement for controlling the alignment of paper sheets in a feed apparatus for printing presses or the like with a photocell arranged on the underside of a sheet retarding hook with a hole therethrough whereby the signal from the photocell is produced when the paper sheet occupies its correct position in the sheet retarding hook.

United States Patent [1 1 Eriksson Aug. 13, 1974 METHOD AND ARRANGEMENT FOR CHECKING THE ALIGNMENT OF A PAPER SHEET IN PAPER SHEET FEED APPARATUS [75] Inventor: Algot Ingemar Eriksson, Solna,

Sweden [73] Assignee: AB Printing Equipment, Sollentuna,

Sweden [22] Filed: Sept. 27, 1972 [21] Appl. N0.: 292,720

[30] Foreign Application Priority Data Oct. 5, 1971 Sweden 12595/71 [52] US. Cl 250/571, 250/234, 271/DIG. 5 [51] Int. Cl. IIOlj 5/16 [58] Field of Search 250/219 DO, 219 DC, 557, 250/571, 234; 27l/DIG. 5, 56

[56] References Cited UNITED STATES PATENTS 3,031,076 4/1962 Declaris et a1 250/219 DQ X 3,278,754 10/1966 Wallace 250/219 DC X 3,569,675 3/1971 Stegeman 250/219 DC X Primary Examiner-Walter Stolwein Attorney, Agent, or FirmOstrolenk, Faber, Gerb & Soffen I 5 7 ABSTRACT A method and an arrangement for controlling the alignment of paper sheets in a feed apparatus for printing presses or the like with a photocell arranged on the underside of a sheet retarding hook with a hole therethrough whereby the signal from the photocell is produced when the paper sheet occupies its correct position in the sheet retarding hook.

6 Claims, 3 Drawing Figures METHOD AND ARRANGEMENT FOR CHECKING THE, ALIGNMENT OF A PAPER SHEET IN PAPER SHEET FEED APPARATUS Special feed apparatus are now used for feeding and aligning paper sheets in printing presses and other paper treating machines. Previously the paper sheets were fed manually, and such procedure is still applied in slow working presses, particularly platen presses, while in the case of modern, rapidly operating machines automatic feed devices are used, and much effort has been made to provide feed means which operate rapidly and without error.

When the paper sheet is removed from a stack of such sheets it is advanced to the receiving machine,'e.g. the printing press, folding machine or similar paper sheet treating machine, normally over a feed table having endless conveyor belts and conveyor rolls. The lower portion of the table serves as a register table having means for aligning the paper sheet. In the case of rapid presses, the conveying means on the feed table are provided with speed retarding means to ensure that the paper sheet arrives at the aligning marks at a speed appropriate therefore. In order to obtain a maximum of time for the aligning work, the next sheet in sequence should be located as close to the alignment markers as possible when the preceding aligned sheet has vacated the markers, for example to obtain smooth operation in stream-fed apparatus with which the sheets slide forward in a continuous stream in overlapping relationship.

The sheets are aligned with the markers, the square, clean-cut leading edge of the sheet and one side edge thereof being moved into abutment therewith. The most conventional method in this respect is the socalled three-point alignment method which employs two front markers and a side marker. With stop cylinder presses the sheetcan be aligned against markers on the stationary cylinder but in the case of two revolution printing presses and other presses with constantly rotating cylinders the front markers may be mounted on the undersurface of the table in a manner to permit them to be lifted up or to be lowered when the sheet is to be engaged by gripping means on the passing cylinder.

Modern paper sheet feed apparatus are also normally provided with automatic stop means comprising signal means and activating means. The signal means, which may be a mechanical detecting probe, an electric slide contact, a photocell or a microswitch, is constructed to send a signal to the activating means in the absence of a sheet in the line or when a sheet arrives too early or is obliquely positioned in relation to the markers, or if several sheets should arrive at the markers simultaneously. The activating means may be operated mechanicaly or electromagnetically and are normally arranged to stop the feed apparatus and printing in the printing press.

In the case of photoelectric signalling means, the photocell is normally placed in plane with the front stop, the speed of the paper sheet normally being retarded before the sheet reaches the stop. If sheet speed retarding hooks and underlying front hold-back means are used, there is a risk that the sheet will lie over the retarding hooks and enter the machine at the wrong point of time.

The present invention relates to a method and an arrangement for controlling the alignment of a paper sheet in a feed apparatus of a paper processing or treatment machine having front alignment markers, sheet speed retarding hooks and means for detecting the position of the paper sheet photoelectrically, characterized in that the photocell of the photoelectric sensing means is arranged on the underside of the sheet speed retarding hook, that a hole is disposed through the sheet retarding hook, and that the signal transmitted by the photocell is produced when the paper sheet occupies its correct position in the sheet retarding hook.

The invention will now be described in more detail with reference to an embodiment thereof illustrated in the accompanying drawings, in which FIG. 1 illustrates a sheet speed retarding hook occupying a neutral position and engaging a paper sheet, FIG. 2 illustrates the sheet retarding means when delivering the sheet to a front hook, and FIG. 3 illustrates the paper sheet retarding hook subsequent to said hook having passed the front hooks.

FIG. 1 illustrates a feed table 1 on which is positioned a paper sheet 2 engaged by a paper sheet retarding hook 3. The hook 3 has an upper, curved portion 4 and is arranged to co-act with a securely connected underlying photocell 5 with a light inlet 6 and a lamp 7. Arranged in the paper sheet retarding hook is a recess 8 having an oblique, rearwardly extending surface 9. The paper sheet retarding hook 3, together with the photocell 5, moves along a path 10 in an upper position towards a front hook 12 which is pivotally mounted about a pivot point 13. The hook 3 continues past the front hook 12 whereafter it is lowered beneath the surface of the table 1 and passes back along the lower part of its movement path, whereafter it is lifted above the surface of the table to the neutral position, ready to receive the next paper sheet.

When the paper sheet passes into the hook, the hole 8 is partially covered by the front edge 11 of the paper sheet. When the hole is free, light from the lamp 7 is reflected away from the photocell by the oblique surface 9 but when a sheet enters the hook, the light is reflected against the surface of the paper into the light inlet 6 of the photocell and a signal is produced. A wrongly aligned paper sheet is illustrated in FIG. 1 by dash lines, the front edge surface 11 of the sheet being located above the upper portion 4 of the hook. In this instance, the light from the lamp is reflected by the oblique surface 9 and not by the paper. The same is true if the paper sheet is obliquely positioned so as not to penetrate sufficiently into the hook to enable enough light to be reflected to produce a signal. The photocell should be so sensitive as to allow a signal to be obtained also in the case of coloured paper or paper carrying black print.

In operation, the photocell and the paper sheet regarding hook move forward and deliver the paper sheet to the front hook. The position of the sheet is constantly checked by the photocell, so that if the paper sheet is drawn to an oblique position the signal will cease. The control signal from the photocell is connected to the paper feed means in a manner to cause said means to stop immediately when the signal is interrupted. Since the stop directly activates the paper feed, only small masses are affected, and hence paper feed can be stopped immediately, e.g. to prevent a paper sheet from entering the press wrongly aligned. Secondly, the pressure between the rolls is removed, and

finally the whole press stops which, however, affects large masses.

FIG. 2 illustrates how the paper sheet has stopped against the front hook 12, and FIG. 3 illustrates how the paper sheet retarding hook 3 has continued beyond the front hook 12 to be lowered while moving down beneath the surface of the table.

For the sake of simplicity, the arrangement has been illustrated with reference to one single retarding hook, although in reality a number of hooks are used to engage along the leading edge of the paper sheet.

Thus, the fault previously occurring as a result of the ability of the sheet to lie on top of the hooks and in spite of this cause signals to be produced is eliminated in a simple manner by means of the present invention owing to the fact that the photocell is positioned so that it will only produce a signal when the paper sheet is exactly in position.

To provide sufficient time in which to stop the feed of the paper sheets in the event of an error, the paper sheet retarding hooks, when occupying their neutral position, are positioned at such a distance upstream of the front hooks that the path travelled by the paper sheet between said hooks corresponds in time to approximately a third of a revolution of the cylinder, although this distance may naturally be varied depending on the type of press being used and the work carried out thereby.

I What is claimed is:

1. An arrangement for checking the alignment of a paper sheet in paper sheet feed apparatus of a paper processing machine having front markers;

at least one movable paper sheet retarding hook having a J-shaped configuration defining a paper receiving slot;

a feed table and means for detecting the position of the paper sheet photoelectrically;

said photoelectric means being fixedly secured to the underside of the paper sheet retarding hook and movable therewith;

said hook having an opening communicating with said slot and said photoelectric means producing a signal responsive to the light reflected from the paper when it arrives in the retarding hook slot in the correct position.

2. The apparatus of claim 1 wherein said photoelectric means comprises a holder containing a photocell and a lamp for producing the signal in the photocell;

said holder having an outlet for passing light from the lamp toward said hook and having an inlet for passing light reflected from the paper sheet toward said photocell;

the light from the lamp being reflected from the paper sheet and passing through said inlet when the paper sheet is correctly positioned within said slot;

the upper portion of the paper sheet retarding hook having an obliquely and downwardly extending surface forming the base of said opening and arranged to reflect light passing through said outlet away from said inlet in the absence of a paper sheet in the paper retarding hook receiving slot.

3. The apparatus of claim 1 wherein the hook is movable downstream to a position beyond the front markers to position the paper feed into the hook and movable beneath the feed table and then upstream to the paper receiving position.

4. A method of checking the alignment of a paper sheet feed apparatus for feeding sheets of paper at high speeds in a paper processing machine, comprising the steps of:

sequentially moving sheets of paper along a surface in a first direction at high speed;

maintaining at a first position a. retarding member having a hook-shaped projection positioned in the path of movement of said paper sheet, said hookshaped projection having an opening;

directing light toward said opening;

detecting light reflecting from the sheet of paper when the leading edge of the sheet is positioned upon said opening to indicate proper positioning of the sheet;

moving the retarding member and the properly positioned sheet at high speed toward a stationary hook-shaped member, located at a second position along said surface, only upondetection of reflected light.

5. The method of claim 4 further comprising the steps of:

moving said retarding member beyond the second position occupied by the stationary hook-shaped member, said sheet being restrained from moving beyond said second position by said stationary hook-shaped member.

6. The method of claim 5 further comprising the steps of:

moving the retarding member away from said surface after passing said second position to move the hook-shaped projection of the retarding member out of the path of movement of paper sheets; and

then moving the retarding member back toward said first position to place the hook-shaped projection in the path of movement of the next paper sheet to be received, said retarding member being moved at a rate sufficient to enable it to return to the first position before receipt of the next paper sheet. 

1. An arrangement for checking the alignment of a paper sheet in paper sheet feed apparatus of a paper processing machine having front markers; at least one movable paper sheet retarding hook having a Jshaped configuration defining a paper receiving slot; a feed table and means for detecting the position of the paper sheet photoelectrically; said photoelectric means being fixedly secured to the underside of the paper sheet retarding hook and movable therewith; said hook having an opening communicating with said slot and said photoelectric means producing a signal responsive to the light reflected from the paper when it arrives in the retarding hook slot in the correct position.
 2. The apparatus of claim 1 wherein said photoelectric means comprises a holder containing a photocell and a lamp for producing the signal in the photocell; said holder having an outlet for passing light from the lamp toward said hook and having an inlet for passing light reflected from the paper sheet toward said photocell; the light from the lamp being reflected from the paper sheet and passing through said inlet when the paper sheet is correctly positioned within said slot; the upper portion of the paper sheet retarding hook having an obliquely and downwardly extending surface forming the base of said opening and arranged to reflect light passing through said outlet away from said inlet in the absence of a paper sheet in the paper retarding hook receiving slot.
 3. The apparatus of claim 1 wherein the hook is movable downstream to a position beyond the front markers to position the paper feed into the hook and movable beneath the feed table and then upstream to the paper receiving position.
 4. A method of checking the alignment of a paper sheet feed apparatus for feeding sheets of paper at high speeds in a paper processing machine, comprising the steps of: sequentially moving sheets of paper along a surface in a first direction at high speed; maintaining at a first position a retarding member having a hook-shaped projection positioned in the path of movement of said paper sheet, said hook-shaped projection having an opening; directing light toward said opening; detecting light reflecting from the sheet of paper when the leading edge of the sheet is positioned upon said opening to indicate proper positioning of the sheet; moving the retarding member and the properly positioned sheet at high speed toward a stationary hook-shaped member, located at a second position along said surface, only upon detection of reflected light.
 5. The method of claim 4 further comprising the steps of: moving said retarding member beyond the second position occupied by the stationary hook-shaped member, said sheet being restrained from moving beyond said second position by said stationary hook-shaped member.
 6. The method of claim 5 further comprising the steps of: moving the retarding member away from said surface after passing said second position to move the hook-shaped projection of the retarding member out of the path of movement of paper sheets; and then moving the retarding member back toward said first position to place the hook-shaped projection in the path of movement of the next paper sheet to be received, said retarding member being moved at a rate sufficient to enable it to return to the first position before receipt of the next paper sheet. 